CCNA 200-125 is a certification exam offered by Cisco that covers a wide range of networking topics including network fundamentals, LAN switching technologies, routing technologies, infrastructure services, and infrastructure maintenance. It is designed to test the skills and knowledge required to install, operate, and troubleshoot small to medium size enterprise branch networks. Passing this exam demonstrates a solid foundation in networking concepts and technologies, making it a valuable certification for IT professionals looking to advance their careers in network administration.